Glowing Animals: Beasts Shining for Science

Crystal Jelly

In 1961 researcher Osamu Shimomura of the Marine Biological Laboratory in Massachusetts noticed a molecule in this jellyfish that glowed bright green under ultraviolet light (as pictured).

After extracting the molecule from 10,000 specimens, Shimomura found the protein that creates the glow.

At some point, a light bulb went off. Some of Shimomura's colleagues realized that the protein could be attached to other proteins--enabling scientists to mark proteins of their choice with a green glow.

Rhesus Macaque Monkey

Scientists at the Yerkes National Primate Research Center in Atlanta are using green fluorescent protein to study Huntington's disease, which destroys nervous tissue.

In 2008 the researchers infected unfertilized monkey eggs with an HIV-like virus, which changed the eggs' DNA to include the defect that causes Huntington's.

The virus also introduced a protein that would make rhesus monkeys fluoresce under ultraviolet light (as pictured)--making it easier to study the effects of the disease on the monkeys' brains.

May 14, 2009

Pig

Photograph by Simon Lin/AP

How does it glow?

Green fluorescent protein, added to embryos (2006)

What can we learn?

Researchers at the National Taiwan University implanted green fluorescent protein into pigs. Seen above in ordinary light, one such pig appears yellowish. Under ultraviolet light, the pigs glow green.

Though earlier experiments had beaten the Taiwanese scientists to the glowing-pig punch, no one else had done it quite as well, the Taiwanese group said: Their pigs glowed inside and out.

The scientists hope to use the fluorescence to track the development of adult stem cells in the pigs, which are genetically very similar to humans.

May 14, 2009

Cat

Photograph by Choi Byung-kil/Yonhap via AP

How does it glow?

Red fluorescent protein, introduced via a virus into cloned DNA, which was implanted in cat eggs, then implanted in mother (2007)

What can we learn?

Scientists at Gyoengsang National University in South Korea both cloned a Turkish Angora house cat and made it fluorescent—as shown in the glowing cat (left) photographed in a dark room under ultraviolet light. (The nonfluorescent cat, at right, appears green in these conditions.)

The scientists weren't the first to clone a cat--they weren't even the first to clone a fluorescent cat. But they were the first to clone a cat that fluoresces red.

It's hoped that the red glow, which appears in every organ of the cats, will improve the study of genetic diseases.

May 14, 2009

Mice

Photograph courtesy University of Pennsylvania

How do they glow?

Green fluorescent protein, received via DNA from father, which had been implanted with glowing sperm-creating cells from a flourescent mouse (2004)

What can we learn?

University of Pennsylvania researchers figured out how to maintain and grow glowing, sperm-creating stem cells from genetically modified fluorescent mice.

The team then implanted the cells into infertile mice, which "miraculously" fathered three of the pups pictured--and the offspring of the lucky mice "men" glowed green under ultraviolet light, tipping the scientists off to their success.

May 14, 2009

Mice

A Harvard team working with mice invented the "brainbow." When three different colors of fluorescent protein--cyan, red, and yellow--were introduced into a mouse embryo, the individual neurons of the mouse's brain became one of 90 different colors.

In addition to looking fantastic, the psychedelic mouse minds will likely lend insight into how brains work.

Tobacco

Iowa State University scientists inserted a genetic structure from fireflies into a tobacco plant, causing it to glow.

Unlike the gleam spurred by green fluorescent protein, the firefly-derived glow--caused by the pigment luciferin and the enzyme luciferase--does not require ultraviolet light to fluoresce. The firefly light, though, does require oxygen and, under some conditions, ATP, a molecule involved in energy storage inside cells.

May 14, 2009

Emperor Scorpion

Photograph by Sam Yeh/AFP/Getty Images

How does it glow?

Beta-carboline, naturally occurring

What can we learn?

Adults of any scorpion species naturally glow green-yellow or blue under ultraviolet light.

First scientifically described in 1954, the phenomenon led to the creation of "scorpion detectors"--black lights--which made camping in scorpion-prone climates a less intimidating proposition.

Using ultraviolet light, scientists have been able to study the scorpions in their native nocturnal habitats without disturbing the animals, which may lead to new insights into how we might avoid them. For example, a 1972 report documented scorpions as high as 8 feet (2.5 meters) in trees.

A 2001 Marshall University paper suggested that--sometime in the past, when the insects may not have been strictly nocturnal--the scorpions may have evolved their UV-reflecting armor as a sort of sunblock.

But arachnophobes, take note: Young scorpions don't glow under ultraviolet light, because the arachnids' fluorescence doesn't develop until later in life.

May 14, 2009

Nematode Worm

Photograph courtesy Ken Norman, University of Utah

How does it glow?

Green fluorescent protein, introduced into its DNA (2005)

What can we learn?

In 2005 University of Utah biologists wanted to study worm rhythm. They isolated a gene they believed to control swallowing, egg laying, and pooping.

To test their hypothesis, the team tagged the gene with green fluorescent protein in a worm. Sure enough, the throat, intestines, and gonads of the animal all glowed green (pictured at right).

To double-check, the team disabled the gene in another worm. That gave them a worm that could not swallow (left), which died at a small size because it could not eat.

The experiment may sound esoteric, but humans have rhythmic activities--swallowing, ovulating, giving birth, defecating--controlled by a similar gene, so the glowing worm could lead to solutions for a variety of ailments.

May 14, 2009

Dog

In the same city that gave the world its first cloned, fluorescent-red cat, another group of Seoul scientists--this time at Seoul National University--engineered the world's first cloned, fluorescent red dog on April 26, 2009.

Ruppy the beagle--a combination of "ruby" and "puppy"--is the first successful clone of a genetically modified dog.

Believe it or not, the glow wasn't the point of the experiment--just evidence of the genetically modified nature of the beast.

The ability to clone genetically modified dogs should improve the study of human genetic diseases in dogs, such as Parkinson's, according to the research team.

Zebrafish

In 1999 scientists at the National University of Singapore began working with zebra fish and green fluorescent protein, hoping to engineer a fish that would glow in the presence of toxic chemicals.

In the process, the scientists created fish that fluoresce all the time (under ultraviolet light) and in a range of colors.

A few years later, the first fluorescent pet hit the market, after Singapore had become the first country to authorize the sale of the genetically modified fish in 2003. Later that year "GloFish" (pictured) debuted in the United States, where in 2009 they retail for five to ten dollars at some pet stores.

Though fluorescent pet fish have spawned no scientific advances, they inspired the creation and clarification of laws governing genetically modified pets. The United States, for example, was initially forced to classify the genetic modification as a drug.

May 14, 2009

Bacteria

Photograph courtesy UC San Diego via AP

How does it glow?

Multiple colors of fluorescent protein, introduced into its DNA (2008)

What can we learn?

One of the team of scientists that won a 2008 Nobel Prize for green fluorescent protein--Osamu Shimomura, Martin Chalfie, and Roger Y. Tsien--couldn't resist showing off their creation a bit. From Tsien's lab comes this artful plate with selectively swabbed fluorescent bacteria.

The discovery of green fluorescent protein by Shimomura in 1956 was the result of crushing countless jellyfish.

After publishing his findings in 1962, Shimomura studied GFP in detail and realized that no extra fuel was needed to make it glow--other glowing substances need chemical additives to shine. GFP, by contrast, just needed to be exposed to ultraviolet light.

Chalfie, the third of the GFP Nobel winners, realized the maintenance-free protein could be used to literally watch how creatures work. He proved with the intestinal bacterium E. coli that GFP alone--with no fuel--glowed, and promptly started putting it into roundworms.

Roger Tsien kicked it up a notch by reengineering GFP to be cyan, blue, and yellow. Yet more colors were found in fluorescent coral. He remixed these materials into glowing proteins such as "mPlum," "mStrawberry," and "mOrange."

Though their inventions may have revolutionized the fields of medicine, biology, and chemistry, the fluorescent proteins also have creative applications, as shown above. Fluorescent proteins have also been used in the name of art to make sculptures out of glowing beakers and live glowing rabbits.